Steam injector



Dec. 2l, 1943. w. H. TINKER y 2,337,283

` STEAM INJECTOR Filed Feb.l 17, 1942 2 Sheets-Sheet 1 Patented Dec. 21, 1943 STEAM INJECTOR Walter H. Tinker, Boston, kMass., yassignor .di fifty-one one-'hundredths vto Edward J. Maillon,

Chillicothe, Ohio Application February 17, 1942, -Serial No. 131,313

(01; ros-"2.65)

9 Claims.

This invention relates to improvements xkin steam injectors. The-general object of the inven- -tion is to provide a simple and reliable feed water heating injector having relatively few parts, 'and lparticularly adapted for steam locomotive `service.

It is within the general Ipurview of the 1invention to provide an injector having a thermal eiiciency, commensurate With its capital cost and maintaining an average high temperature-of the delivery water which tends to improve Vloco- -motive fefiiciency, and to provide a devicesomewhat automatic in its rate of delivery and'of 'the water heating type, controlled by a single lever from the cab on the locomotive.

One of the more specic objects of the invention is to vprovide a steam injector wherein the A:stai-ting, cutting 01T and Iwater delivery regulation are accomplished by the manipulation o'f a single lever or rod which actuates linkage so connected to the live steam valve and water valve as to operate these valves simultaneously through ranges of movement of different amplitude, the water valve moving at the faster rate, saidvalves and the conduits which they control being so correlated that both valves reach their full -delivery capacity early in their respective -rangesbf opening movement and at about the same time, the Water valve rand/or its conduit being fso constructed as to produce a throttling region -within that vpart of the range of movement of said water valve beyond the point at which full capacitydelivery is rst attained, ineiTective whenlthe valves are opened quickly as at starting, but serving vas :a datum for water volume varying movementso'i vsaid Water valve beyond said throttling region when said valves are moved slowly, the corresponding movement of said'live steam valve-tak'- ing place within the full delivery capacity phase ,ofthe range of movement of said live steam valve, `variations `in water delivery being accomplished without corresponding variations in the `1live 'steam jet. This means that the live steam `valve always opens sufticiently to pass an amount of steam commensurate Withlthe amountof water-itc berpumped.

Another object lof the invention is the provi- `sion of an inject-or of the type described, in which Aprovision is made .for the admission of exhaust steam, lwhen available, to the water inlet chamber of theinjectorfor imparting `its modicum `of lheat to the water, said exhaust steam beingfad- `mitted past the check yvalve kwhich opens under fthe pressureof-theexhauststeam and Whichzval-ve -is locked 'closed when-'said injector is cut cli".

A further .object of :the .invention is fthe provisionofa ivelocitytand pressure building :venturi fin -thewater inlet:chambericonronting the exhaust #steam nozzle and discharging iin the region .lof :the live steam yeri'training yriozrzle 4of the injector, whereby Athe vexhaust steam builds up some pres. sure in the water whi'chit :delivers :to the `main lventuri Lof the injector, this `trenturi .having Jno tical embodiment fthereo proceeds.

Inthe drawings which :accompany and form -a partof thefcllow'ing specification, and through- `out t'he `several figures of :which ythe -same .charvacters of V-reerence have beenemployed dto `design nate identical parts:

Figure 1 is a vertical :sect-ion through .an in- --jeotor embodying the principles uof the present invention;

-Figure i2 `isan laxial sectionlthrough theiexhaust `steam check yalve;

Figure- 3 'is la ysimilar view through ithe water :valve vand appurtenant mechanism;

Figure 4 is a cross-section .ltakenalongxthe line 4--4 .of Figure '3;

Figure 51is\a longitudinal `axial section through .the live 4steam valve :taken .at right -iangles .to AFigure l;

Figure 7 .is across-section taken along the line '1l-'I1ofLFigure l; and

Figure :8 is -a longitudinal axial -yiew showinga modication involving Athe water Avalve and the :conduit controlled thereby.

Referring .now iin detail to the several figures, Land `irst :referring to Figure a Whichshows the general layout of ,theiiniec'ton it l :omp1,ises.acas in'g v`| :adapted Ito I'besu'itably secured :to the Aside `.ofilocomotivestructureiby meanssuch as the 'bolts 21Wliichpass throughthe perforated 1lugsl3. lThe vcasing 1| has an yaxial bored extending longitudinally 4therethrough 'having a #removable icap f5 closing its lower end. At its supper endithasith'e lateral-p'ort i6, l(seeialso A,Figure f5), with Awhich 'the :live steam fconduit il communicates, :said con'- adu'it taking l'ive Asteam ffrom 'the Ib'oiler. Below fthe Tli-ve steam port I6 :the casing il 'is provided `to provided with the threaded spigot I4 adapted to4 be connected to the boiler at the point to which the make-up water is to be supplied.

shown at 43 in Figure 5, said valve chamber being normally closed with respect to the live steam forcing and entraining nozzle when the cupshaped member is on its seat, but in communication with said nozzles when the cup-shaped member 40 is lifted from its seat.

A ring nut 4I screws into the upper end of the cup-shaped member 40 and imprisons the head 42 of the operating rod 43, with some lost motion, so that the operating rod may rise a .small distance without lifting the live steam valve. The head 42 when seated, as shown in 'Figure l, makes a steam tight t with the cup- The details of the casing, as above described,

are matters Aof design and maybe varied in any manner desired, without transcending the scope of the invention.

A live steam nozzle which asa whole is-desig-V nated by the reference character I5, communicates with the live steam port 6. This comprises a'cup-shaped valve :chamber I6 having a thread- .ed annular .base screwing into a restriction I1 Vwithin the casing I. A central live steam Ven- ,turi nozzle. I8 is mounted in the lower-end of the :valve chamber I6 communicating'at its lower endwltha velocity and pressure building venturi*` I9.' This venturi is made up of several parts 20, 2I andV 22, provided with the lateral spillways 23, 24 and 25 which communicate with the overflow water chamber 26 within the casing I and the outlet to which chamber is controlled by the overflow valve A9. Y

The` details of construction of this venturi are V -not critical to the invention, but may bedescribed as follows. The connected parts andY `2I1have1a downwardly Iconvergent or velocity building bo-re 21, while the part 22 has the downwardly divergent or pressure building bore 28 opening pinto the pressure water chamber 29, which is` in communication with the delivery lwater spigot I4. The pressure building part 22 is not only connected to the rpart 2| Aby the threaded connection 30, but is also connected -to the-casing AI by the threaded connection 3I `separating the pressure water chamber 29 from the overow chamber 25. The spillways'23 and .24,Yas shown,` are in directcommunication ,with

the overflow chamber 26, while the spillway vis indirect communication with theoverflow 33 which isinV valve communication with the V32, which are water inlet port I2 by means of the water valve 34. The inlet water chamber 33 communicates with a water entraining chamber 35 in the casing I which surrounds the live steamnozzle I8. `The entraining chamber 35 is` separated from the overow chamber 26 by theupper end, of the injectoryenturi I9, which is screwed to the wall of the bore 4,.by thethreaded connection 36. Water from the entraining chamber 35 enters V,the venturi I9 through `the annular passagev31.

. The injector4 is providedV with a live :steam entrainingnozzle 38 which opens into the en- -training 4chamber 35 confronting the annular fpassage 31. Both the live steam forcing nozzle `I8. and thelive steam water entraining Anozzle -38 are in valve control by means of the live steam .valve which as a whole is designated by the-reference character 39.y

The live steam valve comprisesV acup-shaped l:valve member 40, Y operating in `the valve Chamber I5,.that side ofthevalve chamberwhich confrontsgthe live steamfport 6, being open, as

Vas at 56 upon the casing of the injector.

.ondor two.

lshaped member 40 against which it rests.

The water valve comprises a head member 44 which normally rests upon a seat 45 between the inlet port I2 and the water inlet chamber 33. A ring nut 46 screws into the top of the head member 44, imprisoning the enlarged end 41 of a stem 48 which operates the water valve. There is some lost motion between the enlarged end 41 and the ring nut, so that the stem 48 can rise a small distance before the water valve is lifted.

Both the rod 43 and the stem 48 are packed against leakage by the glands 49 and 50, respectively.

The rod 43 and the stem 48 are eachy pivotally connected at the points 5I and 52 toa link 53 pivoted laterally of both said rod and said stem at the point 54 so that when said lever 53 is swung about its pivotal connection 54, said rod and said stem are raised but at an unequal rate, the stem 48 being lifted at a faster ratepthan the rod 43 and therefore having a longer range of movement. Inasmuch as the pivotal connections 5I andr52 move in arcs and it is desired to avoid lateral pressures upon the respective rod 43 and stem 48, the lever 53 is pivotally connected to -a swinging link 55 pivotally mounted The injector is operated by a rod ror lever 51 pivotally connected to the lever 53 and which is pulled upward to open the valves 39 and 34. I

Both the live steam valve 39 and the water 4valve 34 and the conduits which they control are so constructed and designed that they open totheir full respective steam admitting and water admitting capacity at an early period in vopening against steam pressure, and the venturi .would be filled solely with steam and would deliver no water to the'boiler. It is therefore quite essential that water must be entrained withthe steam jet as the latter enters the venturi. Therefore, both'the live rsteam and water valves must be simultaneously opened. Inasmuch as the live steam enters under pressure, it is essential that both the steam and water valves reach their full capacity almost as soon as they are opened, and that the water valve open faster than'the steam valve. YIn the operation of any `injector it is therefore customary to manipulate the'starting level by a quick jerk or by a rapid movement through a time interval of not more than a sec- In the subject injector, starting is accomplished by pulling upwardly upon the leverI 51 by a quick movement, opening both'the live steam `valve 3,9 and the 'water valve 34'througl1 their entire range of movement inV an opening direction. As has 'been.stated, both valves reach their full open capacityat an early point in their respective ranges of opening movement. In order for the live steam to acquire velocity in Athe convergent portion of the venturi l 9, it must `displace the inert water in said venturi, which it does by forcing it through the spillways 23, 24 and 25 into the overflow chamber, at the same ltime carrying with it the entrained water which will be built up in the divergent portion of the venturi to suflicient pressure to lenter the boiler. The Vwater and steam forced out through the spillways 23, '24 and 25 opens the valve 9 and overflows through the port Ail. Normally, Aan injector operates under slightly less than atmospheric pressure, so that vas soon vas the Ainjector is operating, the overflow valve 9 automatically closes .under the reduced pressure within the overflow chamber 26.

At this time a maximum volume of water is being admitted by wayof the water inlet .port I2 and the maximum amount is being delivered to .the boiler. It is, however, desirable to regulate the amount of water delivered vto the boiler, and this should be done withoutdiminishing the force vof the Vlive steam jet beyond that required for the work done. Since the live steam valve 34 reaches its full capacity opening at an early stage in its range of opening movement, and continues to vhave this maximum capacity during the rest of Iits range of opening movement, the present invention takes advantage of this condition by performing the water volume varying movements of the water valve in that part of the range of opening movement of the water valve which corresponds to the full capacity range of movement .of the live steam valve or adjusted so that the live steam valve admits sufficient live steam for Vthe amount of work performed.

In order to do this, the water valve 3d includes :a throttling disk 58 of such size as just to freely pass through the opening in the valve seat 45. This disk is secured axially of the valve head i4 on a stem 59 which extends beneath said valve head. W'hen the valve head A4 is lifted from its seat so that the opening between said valve head and seat is equal to the opening between the disk 58 and said seat, the water valve is open to -full capacity. When the lever 53 is swiftly lifted in starting the injector, the disk 58 passes from the lower side of the seat 45 to the upper side so fast that it has no throttling effect upon the injector, inasmuch as the capacity of the inlet water chamber 33 is suiiicient to meet the de- .mands of the injector during the moment in which the disk 53 is in transit through the plane of the seat 45, and when the water valve 34 is at the extreme upper limit of its range of opening .movement the disk 58 is above the seat d5 a suflicient distance to give the water valve its full open capacity. Thus in starting, the disk 58 has no .throttling eifect.

Now, in regulating the volume of water, the lever 53 is very slowly swung upwardly or downwardly by manipulation ofthe lever 5l, the disk 58 being always above the plane of the seat G5, 'being brought close to said seat to reduce the volume of water delivered, or raised with respect to said seat to increase the volume delivered. The live steam valve, of course, follows the movements of the water valve, but always in that part rof the range of movement of the live steam valve which represents the full open capacity of said valve 'for the amount of water handled, the

amountiof steam valve opening being adjusted 'in extent by the ydesign ibut the downward :movement of the steam 'and water valves eiectually reducing the water passage area but .not decreasing the steam valve area beyond any predetermined point necessary for adequate steam `to water ratio. In cutting olf the injector the 'lever 53 is moved all the way down to seat both the live steam and the water valves in the positions shown in Figure 1. Thus, by the manipulation of a single lever, `both starting and cutting olf of the injector, as well as regulation of the volume of water delivered to the boiler is laccomplished in a simple and eiiicient manner.

Reference may now be had to Figure 8 which shows a modified form of the invention as regards the Vwater valve which amounts to substantially a reversal of parts. In this iorm'of the invention the head 6D of the water valve vis not provided with a disk, but instead, an annular throttling rib 6I is provided on the inside of the valve chamber above the valve seat `E52 rand suit'- ably spaced therefrom. When the valve 6I) is lifted to a position half way between the seat 62 and rib 6l it is in a position of full open vcapacity. 'When it has been lifted to the upper limit of its range of movement, it is still in a position of full open capacity. If the transition is made quickly from its full open position 'bee low the ribv 6I to its full open position above the rib 6I, the throttling effect upon the injector 'is nil, and the inlet water chamber 33 is of sufi cient capacity to supply for an instant the vdemands of the injector. When it is desired Ato regulate the volume of water delivered, this is done while the valve head 60 is above the rib GII'. It is slowly made to approach said rib for reduc'- 'ing the volume delivered, and slowly raised While above said rib for increasing the delivered volume. During these volume regulating movements of the water valve, the live steam valve is making corresponding movements but of less amplitude, and which movements are confined to that part of the range of said live steam valve in which it is adequately open.

Returning now to Figure 1, in order to adjust the time point at which steam enters the forcing nozzle I8 with respect to the time at which the water valve 3d begins to open, the live steam valve 39 is provided with an extension 53 normally entering the upper end `of the forcing nozzle I8 when the live steam valve is closed, and substantially occluding said live steam valve. When the live steam valve is raised, it opens to the entraining nozzle a moment prior to its communication with the bore of the forcing nozzle. This interval can be varied by backing out the ring nut l I, more or less screwing it down against interposed shims (not shown). This varies the lost motion between the head 42 and the ring nut, and permits the extension 63 to be drawn up a greater or lessv distance with respect to the inlet end of the forcing nozzle I8 before the valve 39 raises from its seat.

The exhaust steam from the cylinders of the locomotive, when present, is employed to impart its quota of heat to the water, and to correspondingly increase the efficiency of the locomotive op.- eration. The exhaust steam enters the injector through a conduit connected to the spigot I3, and passes through the adjacent portion 64 of an exhaust steam nozzle 65, the bore of which is intersected by the gate valve 65. Said gate valve *when in its lowermost position, as shown, closes the "bore 'through the exhaust steam nozzle. '-It has a port 61 which registers with the bore in the exhaust steam nozzle when the gate valve is in elevated position. The gate valve is connected at the lower end of the valve rod 68 provided with a head 69 retained within a recess in the gate valve, with some lost motion between said valve and stem. The lower part of the gate valve 66 is received in a chamber 10 formed inthe fitting H. f

Above the exhaust steam nozzle (i5,` the Vfitting Il is formed as a cylinder 1I, in which a. plunger 12V operates, the valve rod 68 being secured to said plunger and extending therebeyond, through an aperture in the top of said cylinder and terminating beneath the lever 53. The valve rod68 makes a loose fit where it passes through the top of the cylinder, permitting atmospheric leakage into the cylinder chamber above the plunger so that the latter can descend gravitationally when not sustained by exhaust steam pressure. When the lever 53 is in the closed position with respect to the live steam and water valves, it contacts the top of the valve rod 68 and locks the gate valve shut. v

There is a port 13 provided between the exhaust steam supply chamber and the lcylinder chamber 14 beneath the plunger, so that when exhaust steam reaches the closed gate valve` it simultaneously acts upon the plunger via port13, lifting it, so as to open the gate valve. The fore ward end of the exhaust steam nozzle confronts the convergent endk of a venturi 15, which venturi forms a conduit forthe water and exhaust steam delivering the water to the entraining chamber 35 of the venturi I9. The forward end of the exhaust steam nozzle is of smaller diameter than the adjacent end of the venturi 15 dening an annular space 16 in the inlet water chamber 33 through which water is entrained into the venturi 15 by the jet of exhaust steam issuing from the exhaust steam nozzle. The venturi 15 has a pressure building portion 16 opening adjacent the entraining passage 31 of the main venturi. Thus, some water pressure is built up by the exhaust steam in the region of its induction into the main venturi. The water is heated by the exhaust steam.

The chamber 16 formed in part Il, which chamber 10 extends all the way around nozzles 64 and 65, contains a pressure very nearly equal to that at the throat gap between nozzles 64 and 65 and the leakage steam around valve-rod 68 from chamber 14 is absorbed by nozzle 65. When valve 66 is closed (in farthest downward posi-A tion shown in Figure 1) it acts as a non-return valve in either direction of attempted flow through the nozzle parts 64 and 65. 1 Inasmuch as there are occasions in which the injector operates with the overflow chamber 26 under a pressure somewhat greater than atmosphere pressure, means are provided Vfor holding the overflow valve 9 closed during such operation. Figure l shows that the valve 9 is provided with a stem 13 which telescopes within a closedtopped plunger 18 slidable within a tubular guide 80 formed on the inner side of a removable cap 8l which closes an aperture in the casing I above the valve 9. The tubular'guide is in turn-closed by a cap B2 connected by a tube 33 to a force of steam supply, said tube having a valve 84 by means of which the steam may be cut on or off.

Ordinarily, the cushion of air within the plunger chamber is suiciently compressibleto permit the valve 9 to lift under the overflow pres-v sure in the overdow chamber 26. ,When desir'ed to positively hold the" valve 5 closed, steam is turned into the plunger chamber 85, depressing the plunger, Ythe top of which abuts against the valve stem and holds the valve down to its seat.

'.When there is no exhaust steam present, the exhaust steam valve 66 remains closed by gravity, andthe injector koperates solely through lthe agency of the live steam.

It is obvious to those skilled in the art that my improved injector, as disclosed, simplifies the opera-tion by providing that not only starting and cutting off of the injector, but regulation of the volume of water delivered to the boiler may be readily accomplished by the manipulation of a singlehandle or lever, moving it quickly throughout its entire range of movement for starting, and then moving it slowly Within the upper part of its range of movement for varying the 'water supply to the injector without varying the steam supplied thereto, and that cutting off of the injector is accomplished by moving the handleor lever in the opposite direction throughout its entire range of movement. It is also obvious that I have provided an injector in which the heat and velocity of exhaust steam when such steam is available are conserved and made to do useful work in the injector and which correspondingly enhance the boiler efficiency of the locomotive'. It is also apparent that no attention whatsoever need be paid to the exhaust steam. When present, it automatically enters the injector and performs its function. When not present, the exhaust steam valve automatically remains closed', and when the injector is cut off, the exhaust steam valve is automatically locked closed, so that if exhaust steam should be present at the locomotive side of the valve 66, it cannot enter the injector.

While I have in the above description disclosed what I believe to be a preferred and practical embodiment of my invention, characterized by relatively few parts and simplicity in design, construction and assemblage, it will be understood to those skilled in the art that the details of construction and the arrangement of parts are largely by way of illustration and not to be construed as limiting the scope of the invention which is dened in the appended claims.

What I claim as my invention is:

1. Steam injector with variable water volume delivery comprising a venturi, a Water supply conduit leading thereto, a steam supply conduit communicating therewith divided into a forcing nozzle and an entraining nozzle, the latter being positioned in waterentraining relation to said Water supply conduit, valves in said steam supply conduit and in said water supply conduit movable together at proportionate speeds, said Valves each having a closed position, a full capacity open position, and a range of further movement be@ yond the full capacity open position, said water supply conduit having a bore constriction, and cooperating structure of the water supply conduit valve forming with said bore constriction throttling means for said water supply conduit, said cooperating structure having a normal range 'of throttling movement substantially limited to that phase of the movement of said valves which takes place beyond their full capacity open po sition.

2. Steam injector with variable water volume delivery comprising a venturi, a water supply conduit leading thereto, a steam supply conduit communicating therewith divided into a forcing nozzle and an entrainingnozzle, the latter being 'positioned in waterentraining relation to said water supply conduit, valves in sai-d steam supply vconduit and in said water supply conduit movable together at proportionate speeds, said valves each having a closed position, a full capacity open position, and a range of further movement beyond the full capacity open position, said water supply conduit having a bore constriction, and cooperating structure of the water supply conduit valve forming with said bore constriction throttling means for said water supply conduit, said cooperating structure having a normal range of throttling movement substantially limited to that phase of the movement of said valves which takes place beyond their full capacity open position, said constriction being located between the throttle forming structure of said water supply conduit valve when said valve is closed, and the full capacity open position of said valve so as to be passed momentarily by said throttle forming structure in the movement of said valve from closed to full capacity open position, the capacity of said water supply conduit between said water supply conduit valve and said entraining nozzle being sufcient to continue to supply the injector during the momentary passage of said valve structure past said constriction, whereby the momentary throttling eiect of said passage is nulliiied.

3. Steam injector as claimed in claim 2, the said cooperating structure comprising a disk secured in spaced relation to the water supply conduit valve.

4. In a steam injector, a venturi having a forcing nozzle and an entraining nozzle both communicating with a live steam supply, and means providing a water supply conduit communicating with said venturi at the mouth of said entraining nozzle, a live steam valve and a water valve respectively controlling the supply of live steam and water to said venturi, said live steam valve comprising a member controlling the admission of steam to the forcing nozzle, a lever connecting said forcing nozzle controlling member and said water valve for effecting their simultaneous operation at proportionate speeds, the water valve opening at a faster rate, said valves reaching their full capacity -open position early in their respective ranges of opening movement, said live steam valve also including a member controlling the admission of steam to the entraining nozzle, actuated by said vforcing nozzle controlling member after some lost motion between said members at the beginning of the valve opening movement of said lever, and means for adjustably varying the lost motion between said members to vary the synchronization of the opening of said live steam and water valves, said water supply conduit havinga bore constriction, and cooperating structure of the water supply conduit valve forming with said bore constriction throttling means for'said water supply conduit, said cooperating structure having a normal range of throttling movement substantially limited to that phase of the movement of said valves which takes place beyond their full capacity open position.

5. In a steam injector, a venturi having a live steam supplied forcing nozzle and a live steam supplied water-entraining nozzle, means forming a water conduit communicating with a water supply and with said venturi at the mouth of said water-entraining nozzle, an exhaust steam nozzle communicating with a source where exhaust steam may or may not be present discharging into saidy water conduit dependently upon the presence of exhaust steam at said source, a live steam valve and a water valve respectively controlling the admission of live steam to said forcing and entraining nozzles and the admission of water tov said conduit, means for manually operating. 'said valves, and a valve controlling the admission of exhaust steam to said exhaust steam nozzle automatically actuated through pressure of the exhaust steam at said source.

6. In a steam injector, a venturi having a live steam supplied forcing nozzle and a live steam supplied water-entraining nozzle, means forming a water conduit communicating with said venturi at the mouth of said water-entraining nozzle, an exhaust steam nozzle discharging into said water conduit, a live steam valve and a water valve respectively controlling the admission of live steam to said forcing and entraining nozzles, and the admission of water to said conduit, a lever for simultaneousli7 operating said valves, to which said valves are commonly connected at different distances from the fulcrum of said lever for moving said valves at proportionate speeds, the water valve moving at the faster rate, a valve controlling the admission of exhaust steam to said exhaust steam nozzle, and Ioperating means therefor comprising a cylinder, a stem for said valve passing through said cylinder, a plunger on said stem within said cylinder actuated by exhaust steam pressure for opening said exhaust steam'valve, said lever overlying said valve stem in locking relation thereto when all three valves re in closed position.

'7. In a steain injector a main venturi having a forcing nozzle and a water entraining nozzle, means forming a water conduit communicating with a water supply and with said main venturi at the mouth of said water entraining nozzle, a part of said water conduit being an auxiliary venturi with its pressure end toward said main venturi, an exhaust steam nozzle extending into said water conduit into entraining relation to said auxiliary venturi and communicating with a source where exhaust steam may be present, a normally closed exhaust valve controlling said exhaust steam nozzle, opened by exhaust steam pressure from said source, and valves operable independently of said exhaust steam valve, controlling respectively the :admission of live steam to said main venturi and water to said Water conduit, whereby said auxiliary venturi functions alternatively, in the absence of exhaust steam as a mere conduit supplying said main venturi, and in the presence of exhaust steam to deliver additional water, heated and with pressure, to said main venturi.

8. In a steam injector, a venturi havin-g a live steam supply and a conduit from a water supply communicating therewith, correlated live steam and Water valves controlling respectively the supply of live steam and water to said venturi, said conduit including a preheater for the Water supplied to said venturi, in communication with a source at which exhaust steam may or may not be present, and activated dependently upon the presence of exhaust steam, and a normally closed valve controlling the admission of exhaust steam to said heater, automatically opened by pressure of exhaust steam from said source.

9. In a steam injector, -a venturi having a live steam supply and a conduit from a water supply communicating therewith, ccrrelatedlive steam and water valves controlling respectively the supply of live steam and water to said venturi, said f conduit includingra preheaterrfor the water supplied to said venturi, in communication with a source at which exhaust steam may or may not be present, and activated dependently upon the 'presence of exhaust steam, and a normally closed valve controlling the admission of Yexhaust steam to said heater, automatically -opened by pressure 

